Device for fixing the front end assembly of a motorcycle with caster angle and adjustable ground caster angle

ABSTRACT

Device for fixing the front end assembly of a motorcycle includes an upper plate, a lower plate, a column shaft linking the two plates by enclosing the chassis column tube. The bearings originally mounted are replaced by an assembly of parts and the swivel joint element. The rotating elements are placed in the plate and the plate respectively to allow them to rotate on the column shaft locked in rotation by the part. The groove of the part and the cylindrical surfaces of parts with axis perpendicular to a median plane of the vehicle and passing through the center of the swivel joint allow the entire device to pivot about the axis to offset the column shaft with the axis of the tube thereby modifying the caster angle. The rotating element mounted in an oblong configuration enables the offset on the plate to be modified and by tilting about the axis and tilting of the plate about the axis enables the value of the ground caster distance and the inclination of the suspension element to be modified.

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

The invention involves a device for fixing the front end assembly of amotorcycle, allowing a modification of the parameters that define thedynamic qualities of the vehicle and notably the caster angle and thevalue of the ground caster distance.

BACKGROUND OF THE INVENTION

For clarity of the present description, at first the current fashionmost used by motorcycle manufacturers to create the fixation of thefront end assembly will be explained in reference to FIG. 1, FIG. 2 andFIG. 3. FIG. 1 shows a drawing of the front end assembly of a motorcyclemade in its median plane. FIG. 2 shows the same drawing but in a frontview. FIG. 3 shows the detailed mounting of the steering column by asection I-I of FIG. 2 going along its axis of rotation.

It is known that on a motorcycle, the front wheel (1) is, in the largestmajority of constructions, held by the front suspension element which iscomprised of two parallel and telescopic legs (2 a) and (2 b), ensuringthe functions of guiding, suspension and damping, and arranged on bothsides of the wheel, on its axis of rotation and perpendicular to it.These two elements are connected at their upper part by two plates. Anupper plate (3) is arranged at their upper end and a lower plate (4) isplaced below the upper one and at a distance that allows the wheel tohave freedom of movement in its oscillations. These two plates fittightly around the steering column of the chassis.

The steering column is the front part of the chassis. It is comprised ofa tube (5) in which are arranged, at each end, guide mechanisms (6 a)and (6 b) allowing the rotation of a shaft (7) that pass through themalong the axis of the tube (5). This shaft (7) is called the “axis ofthe steering column.” It is affixed in the middle of the lower plate(4), passes through the steering column of the chassis in going into theguide mechanisms (6 a) and (6 b), then passes through the upper plate(3).

A rotation function is thus created between the chassis and the frontend assembly. Using the handlebars (8) affixed onto the upper plate (3),the driver can change direction by rotating the front end assembly andthus the front wheel.

FIG. 3 shows a construction that is currently used, as a non-restrictiveexample, of a mounting of the steering column. Here, the guidemechanisms (6 a) and (6 b) are represented by the tapered rollerbearings, mounted clamped into the receptacles of the column (5), inopposition and in an O. The nut (9) makes it possible to adjust the playnecessary for the rotation of the bearings. The locknut (10) locks theassembly while preserving this functional play.

In order to give stability to the vehicle, the axis of rotation isinclined to the front in a manner so that the axis of rotation of thefront wheel is in front of the steering column. The angle (A) formed bythe perpendicular to the ground and the axis of rotation is called the“caster angle”. The distance (C) between the projection of the axis ofrotation onto the ground and the point of contact of the wheel with theground is called the “ground caster distance”.

It is very important in the study of a motorcycle to correctly choosethe values of the caster angle and the ground caster distance in orderto obtain the dynamic behavior of the vehicle that the majority of usersdesire to have for the specific use defined by the manufacturer'sspecifications. Thus, these values will be very different for amotorcycle planned, for example, for road usage where the caster angleis preferably between 20° and 24° and a motorcycle planned forall-terrain usage where the angle is preferably between 24° and 28 °.

Once the vehicle is made, these values can no longer be modified becausethe caster angle (A) is defined by the angle of the tube of the column(5) welded onto the chassis and the ground caster distance (C) isdefined by the caster angle, the offset (B) made to the plates (3) and(4) and the possible offset (D) made to the fixation of the axle of thefront wheel onto the legs of the suspension (2 a) and (2 b).

In the context of a usage that is more highly specialized and notably incompetition, a large number of users want to optimize the values (A) and(C) as a function of their style of driving and the various accessoriesof their vehicle. To modify the ground caster distance (C), it ispossible to replace the plates (3) and (4) with plates having adifferent offset (B) and to replace the suspension legs (2 a) and (2 b)with legs having a different offset (D). To do this, it is necessary tohave as many plates and legs as there are values to attempt.

The modification of the caster angle (A) is made in some racing teams byusing interchangeable rings that allow offsetting of the axle (7)relative to the column tube (5). The implementation of these rings makesnecessary a significant and expensive modification of the tube (5) ofthe steering column used on competitive vehicles coming frommass-produced models. Moreover, each ring gives a fixed value of theangle (A) and the change of the ring requires the dismounting of thefront end assembly and in particular, the plates (3) and (4). Thesesignificant interventions produce an equivalent reduction in theduration of the testing sessions that are limited in time.

BRIEF SUMMARY OF THE INVENTION

The present invention proposes an assembly of upper and lower plates andcolumn shaft which is able to be mounted easily on the column (5) of themotorcycle chassis used by the manufacturers in mass-production, whichoffers the particularity of being able to make the caster angle (A) varymore or less on the order of 1° to 3° and the offset (B) in anindependent manner on the upper and lower plates. These adjustmentmodifications can be made quickly without dismounting the front endassembly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

More specifically, and in referring to the attached drawings, given asnon-restrictive examples, where the different preferred embodiments ofthe invention are shown,

in addition to FIG. 1,

FIG. 2 and

FIG. 3 described above:

FIG. 4 is a section I-I of FIG. 2 of the mounting of the steering columnthat allows unique regulation of the caster angle (A), in a middleposition.

FIG. 5 is a section II-II of FIG. 4.

FIG. 6 is a section identical to FIG. 4 but in an extreme adjustmentposition.

FIG. 7 is a section according to III-III of FIG. 4.

FIG. 8 is the enlarged detail IV of the surfaces (20) and (21).

FIG. 9 is a section I-I of FIG. 2 of the mounting of the steering columnthat allows the regulation of the caster angle (A) and the regulation ofthe offset (B) unique to the upper plate, in a middle position.

FIG. 10 is a section V-V of FIG. 9.

FIG. 11 is a section identical to FIG. 9 but in an extreme position foradjustment of the offset on the upper plate.

FIG. 12 is a section along VI-VI of FIG. 9.

FIG. 13 is a section along VII-VII of FIG. 9.

FIG. 14 is a drawing similar to that of FIG. 1 but with the adjustmentof FIG. 11.

FIG. 15 is a section I-I of FIG. 2 of the mounting of the steeringcolumn that allows regulation of the caster angle (A) and regulation ofthe offset (B) on the two upper and lower plates, in the middleposition.

FIG. 16 is a section VIII-VIII of FIG. 15.

FIG. 17 is a section I-I of FIG. 2 of the mounting of the steeringcolumn that allows the exclusive regulation of the caster angle (A), ina middle position and mounted in a manner that is inverted from themounting of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 4, FIG. 5, FIG. 6 and FIG. 7 show, as a non-restrictive example, aconstruction of a device according to the invention but only allowingthe exclusive regulation of the caster angle. In this mounting, thecolumn tube (5) of the chassis is kept but the guide elements (6 a) and(6 b) of FIG. 3, ensuring the rotation of the front end assemblyrelative to the chassis, are replaced respectively by the elements (16)and (11) placed respectively in the upper plate (33) and lower plate(34). In this way, the rotation of the front end assembly is preservedin spite of the blocking of rotation of the axle of the column (37).

The axle (37) passes through the guide element (11), shown here, as anon-restrictive example, as a double row ball bearing and affixed in anappropriate manner in the plate (34), as (non-restrictive example) aclamped fitting and machined support, in a manner so as to support theaxial loads directed to the top and transmitted by the front endassembly through the plate (34), through an angular contact bearing (12)arranged in place of the guide element (6 b) of FIG. 3 in the tube (5),in an appropriate manner, and able to support the axial forcestransmitted by the element (11).

A spacer (24) can be arranged between the elements (11) and (12) inorder to guarantee a minimum distance between the top of the plate (34)and the bottom of the tube (5) in order to allow the tilting movement ofthe plate (34). This spacer (24) can also be provided with any means ofsealing in order to protect the elements (11) and (12).

In its upper part, the axle (37) goes through a guide part (14) affixedinstead of and in place of the element (6 a) of FIG. 3 in the tube (5),in an appropriate manner and as a non-restrictive example, by tightfitting and locking screw (13) preventing any rotational movement of thepart (14) in the tube (5). The part (14) has a groove with parallelsides (18 a) and (18 b). The axis of this groove must be arranged in theplane of FIG. 4, i.e. more precisely, in the plane of FIG. 1 which isthe median plane of the vehicle and the plane that defines the casterangle (A).

On the axle (37), two planar surfaces having parallel sides (19 a) and(19 b) are made with dimensions that allow them to slide without play onthe respective sides (18 a) and (18 b) of the groove of the part (14).

The upper surface (20) of the part (14) is a cylindrical portion of theaxis (30) perpendicular to the sides (18 a) and (18 b) of the groove andpassing through the center of rotation of the bearing (12). The part(15) arranged above the part (14) has a lower cylindrical surface (21)combined with the surface (20) in a manner so that the part (15) canslide on the part (14) while rotating around the axle (30) of thecylindrical surfaces. The part (15) is opened in its middle andperpendicularly to the axle (30) of the cylindrical surface in order toallow the passage of the top of the axis of the column (37).

The axle (37) then goes through the guide element (16), represented hereas a non-restrictive example by a deep groove ball bearing, affixed inan appropriate manner in the upper plate (33) and notably by a clampedfitting and retaining circlips (17), goes through the spacer (22) onwhich a locknut (23) rests.

When the nut (23) is not being clamped, it is possible to rotate all ofthe front end assembly around the axle (30), guided by the sliding ofthe sides (19 a) and (19 b) of the axle (37) on the sides (18 a) and (18b) of the groove of part (14) and the sliding of the cylindrical surface(21) of the part (15) on the combined surface (20) of the part (14).Once positioned at the value (E) of FIG. 6 corresponding to the desiredmodification value of the caster angle (A), the nut (23) is clamped in amanner appropriate for locking this position by the adhesion of thesurfaces (20) and (21).

To ensure an effective locking and prevent any risk of sliding of thesurface (21) on the surface (20) subjected to significant stressestransmitted by the front end assembly in the braking phase or the strongcompression of the suspension, it is necessary to tighten the nut (23)very strongly, on the order of 10 to 15 m.kg.

In order to prevent a tightening that is too sizeable and ensure perfectlocking, it is advantageous to create a locking using a stop and not bypure adhesion by creating small grooves on the surfaces so that thesurface (21) engages perfectly on the surface (20) as shown in FIG. 8.These grooves are made on the lines parallel to the axle (30) of thecylindrical surfaces (20) and (21). They are shown here asnon-restrictive examples in a triangular section and allow an angularadjustment by steps (a) on the order of 0.1° to 0.50 °.

It should be noted that the device mounted in an inverted manner fromthat of FIG. 4 also makes it possible to regulate the caster angle (A).The adjustment nut (23) can also and independently be positioned beneaththe plate (34).

FIG. 17 shows such a mounting where the swivel joint element (12) ismounted in place of the upper guide element (6 a), and the guide part(14) in place of the lower guide element (6 b). The part (15) is thenfound beneath the part (14) and their respective cylindrical surfaces(21) and (20) always have their axis common with the swiveling center(30) of the element (12). Here, the axle of the column (37) is mountedin the reverse direction of FIG. 4, and the locknut (23) is positionedbelow the plate (34). The nut (23) is supported on the spacer (722)fitted to the dimensions of the bearing (11) and the axle (37). Theplate (73), the bearing (716) and the spacer (724) are modified to theinverted mounting.

FIG. 9, FIG. 10, FIG. 11, FIG. 12 and FIG. 13 show, as a non-restrictiveexample, a construction of a device according to the invention and ofthe same type as that of FIG. 4 and FIG. 5 onto which the independentadjustment of the offset (B) on the upper plate (43) has been added.

In this construction, the deep groove ball bearings (11) and (16) ofFIG. 4 are replaced respectively and as a non-restrictive example, withthe spherical roller bearings (411) and (416). The bearing (411) ismounted in an appropriate manner on the lower plate (44) with, as anon-restrictive example, a clamped fitting and supported on the plate(44) in a manner so as to effectively support the axial stressestransmitted by the front end assembly.

The bearing (416) is affixed on the upper plate (43) in a receptacle (28a) having an angular shape and dimension allowing displacement, withoutlateral play, of the bearing (416) over a distance of (+e) or (−e). Theaxle of this angular shape (28 a), defining the direction ofdisplacement of the bearing (416), is contained in the plane of FIG. 9which is the median plane of the vehicle, as represented in FIG. 12 andFIG. 13. A locking part (25) limits the vertical movement of the bearing(416). This part (25) is held on the plate (43) by, as a non-restrictiveexample, four screws (26) in a manner so that the movement of thebearing occurs without vertical play. An opening having an oblong shape(28 b) is made in the center of the part (25) in a manner so as to allowdisplacement with play of the spacer (22). A similar oblong shape (28 c)is made in the bottom of the plate (43) in order to allow thedisplacement, with play, of the collar of the part (15). The two shapes(28 b) and (28 c) have their axes contained also in the median plane ofthe vehicle.

As a non-restrictive example, two adjustment screws (27 a) and (27 b)make it possible to displace and position the bearing (416) at aposition (B′) between (B−e) and (B+e). The new value (B′) of the offsetof the upper plate (43) linked to the offset (B) de the lower plate (44)causes an angle (b) between the axis of rotation of the axis of thecolumn (47) and the axis of the suspension legs (2 a) and (2 b). Thisincline is made possible by the tilting of the plates (43) and (44) overrespectively the bearing axes (32) and (31) of the bearings (416) and(411). In FIG. 14 it is noted that the incline (b) due to the offsets(B′) and (B) causes a modification of the ground caster distance (C′)different from the value (C) of FIG. 1.

FIG. 15 and FIG. 16 show, as a non-restrictive example, a thirdconstruction according to the invention and of the same type as that ofFIG. 9 and FIG. 10, to which the independent adjustment of the offset(B) on the lower plate (64) has been added.

In this construction, the bearing (411) is mounted on the plate (64) ina manner identical to the mounting of the bearing (416) on the plate(43). Thus the part (25), the shapes (28 a), (28 b) and (28 c) of themounting of the upper plate (43) are respectively the part (35) and theshapes (29 a), (29 b) and (29 c). Two screws (36 a) and (36 b) similarto the screws (27 a) and (27 b) of the plate (43) also allow thedisplacement and the positioning of the bearing (411) in the plate (64)and at a position between (B−f) and (B+f) with (f) representing themaximum displacement of the bearing (411) more or less in the plate (64)relative to its middle position.

Also appearing on the mounting of FIG. 15, as a non-restrictive example,are two screws (613 a) and (613 b) which allow the displacement and thepositioning of the axle (67) in rotation on the axle (30) during theperiod of adjustment of the caster angle. This mounting can be used inreplacement or with the grooves of the surfaces (20) and (21) FIG. 8.These two screws screw into the tapped holes made, as a non-restrictiveexample, through parts (5) and (14), after having correctly positionedthe part (14) in the tube (5).

1. Device for fixing the a front end assembly of a motorcycle, saiddevice comprising: an upper plate, a lower plate, a column shaftconnecting the lower plate and the upper plate by going through a columntube of a chassis, further comprising: a guide part and a swivel jointelement placed respectively or inversely in upper and lower receptaclesof guide elements of the column tube and placed by manufacturers inorder to allow rotation of the front end assembly, the two elementsbeing passed through by the column shaft, the rotating elements andbeing placed respectively in the lower plate and upper plate in order topermit rotation of these plates on the column shaft immobilized inrotation relative to the tube (5), and a part sliding on the guide partwhile holding the axle which goes through said guide part, being placedbetween the guide part and the upper plate, an assembly thereof of thefront end assembly being comprised of two equipped plates, the part, andthe column shaft, being able to tilt by sliding of the part holding theaxle, on the part united with the tube and guiding the axle in movementin a median plane of the motorcycle and around the axis of rotationperpendicular to the median plane of the motorcycle and goes through abearing center of the swivel joint element.
 2. Device according to claim1, wherein said upper surface of the guide part and the lower surface ofthe part are cylindrical surfaces of the axis perpendicular to themedian plane of the motorcycle and going through the center of rotationof the swivel joint element.
 3. Device according to claim 1, furthercomprising a groove having parallel sides in the guide part so that theaxle of this groove is contained in the median plane of the motorcycleand that the column shaft is slidable without play along said groove by,an intermediary of the two flat surfaces on the shaft.
 4. Deviceaccording to claim 1, further comprising an element preventing rotationof the guide part relative to the tube.
 5. Device according to claim 1,further comprising a nut positioned at either of the two ends of thecolumn shaft, the second end having a stop, locking a position of theshaft at the desired angular value while adhesion of the cylindricalsurface of the part on the cylindrical surface of the guide part bypressure created by the compression of the parts between said nut andstop of the axle.
 6. Device according to claim 5, further comprising, onthe cylindrical surface of the part, small grooves over lines parallelto the axis of the surface, engageable perfectly with the combinedgrooves made on the surface of the guide part, thus an angularadjustment of the axle relative to the tube by steps of value and alocking into position by positive locking.
 7. Device according to claim5, further comprising two opposing threaded holes having an axiscontained in the median plane of the motorcycle through the guide partor the tube or both, allowing two screws to adjust and lock the angularposition of the column shaft relative to the tube axis.
 8. Deviceaccording to claim 1, wherein the rotating elements is fixed by a parton the upper plate in a receptacle having an oblong shape, with an axiscontained in the median plane of the motorcycle, able to allow slidingwithout play and to allow the positioning of the rotating element usingadjustment screws in order to modify the offset on the upper plate to avalue (B′) between (B−e) and (B+e).
 9. Device according to claim 1,wherein the rotating element is fixed by a part on the lower plate in areceptacle having an oblong shape, with an axis contained in the medianplane of the motorcycle, enabling the rotating element to be slidwithout play and enabling positioning thereof using the adjustmentscrews in order to modify the offset (B) on the lower plate to a value(B″) between (B−f) and (B+f).
 10. Device according to claim 8, whereinrotating elements respectively placed in the upper plate and lower platehave a freedom of bearing rotation around the respective axes swingingof the upper plate and lower plate around these axes.